2001 F-250 7.3. The auto lock hubs are not working on the truck lock hubs in and all works fine. First thought is the vacuum system has a leak or something of the sort. Had truck at the shop they are telling me the GEM module controls the vacuum to engage the auto hubs and the signal is not coming from the GEM and it need to be replaced. Just looking for some thoughts or if this has happened to anyone and it was the GEM causing the problem.

Thanks

 

There has been many Post on here for this issue, I do not remember any , that had a gem module, as the cause.
I have been mistaken before, just do a search.
The reason I say I don't believe this to be true is, because you said it works if you manually en gauge the hubs , it works.
Either do the diagnosis yourself , of find another shop .

 

Long story short told shop not to replace the GEM module cause I didn't think that was the issue they put new seals in the axel for the vacuum and auto locks are working fine now.

 

That's very common with the factory hubs. Next time you can fix them yourself of just install manual locking hubs.

 

Glad it worked out for you .
Seals are a lot less loot than a gem module .
As was said , you can do that repair on your own , save 80 to a hundred dollars and hour in labor .

 

Yeah would have done myself but time was of the essence and needed the truck. Unfortunately I had just done new rotors and calipers like 3 weeks before I had it all apart but everything was working fine at that time so didn't even pull the hubs off. Guess I should have been thinking preventative. Thanks for the advice and reassurance on my thoughts

 

critical piece on information here that was left out of the original post.